Election index

Election indices The figures below represent the values of three indices: (i) the least squares index (LSq), which measures disproportionality between the distributions of votes and of seats; (ii) the effective number of parties at the electoral level (Eff Nv, also termed ENEP); (iii) the effective number of parties at the parliamentary or legislative level (Eff Ns, also termed ENPP). The N ofseats refers to the number given in the sources used and is the number on which the calculations were based (though see point (i) below). These indices were originally outlined in Markku Laakso and Rein Taagepera, ‘ “Effective” number of parties: a measure with application to west Europe’, Comparative Political Studies 12:1 (1979), pp. 3–27 (effective number of parties), and Michael Gallagher,‘Proportionality, disproportionality and electoral systems’, Electoral Studies 10:1 (1991), pp. 33–51 (least squares index). Details of these indices, and of how they have been calculated, can be found in Appendix B of: Michael Gallagher and Paul Mitchell (eds), The Politics of Electoral Systems paperback edition (Oxford and New York: Oxford University Press, 2008). For further details on this book, see: http://www.oup.com/uk/catalogue/?ci=9780199238675 The main sources for the election results from which these indices are calculated are: Thomas T. Mackie and Richard Rose, The International Almanac of Electoral History, 3rd ed (Basingstoke: Macmillan, 1991); Annual Data Section in European Journal of Political Research since 1990; Richard Rose and Neil Munro, Elections and Parties in NewEuropean Democracies (Washington: CQ Press, 2003); Dieter Nohlen, Michael Krennerich and Bernhard Thibaut (eds), Elections in Africa: a data handbook (Oxford: Oxford University Press, 1999); Dieter Nohlen, Florian Grotz and Christof Hartmann (eds), Elections in Asia and the Pacific: a data handbook, 2 vols (Oxford: Oxford University Press, 2001); Dieter Nohlen (ed.), Elections in the Americas: a datahandbook, 2 vols (Oxford: Oxford University Press, 2005); and, for recent elections in particular, a range of internet sites, where possible official ones, a list of which is given in Appendix E of Gallagher and Mitchell (eds), The Politics of Electoral Systems. An additional and very useful site, not listed there, is the African Elections Database at http://africanelections.tripod.com/ While anyuser of these sources must appreciate the time that has been spent in compiling them and the care taken to ensure accuracy, the main problems associated with sources (and, implicitly, the main appeals to those who compile election results) are:

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(i) occasional logical inconsistency, i.e. the number of votes or seats for the listed parties does not add to the stated total,or a party with no votes is stated to have won seats. A list of corrections that need to be made to the Mackie and Rose figures can be found in Arend Lijphart, Electoral Systems and Party Systems: A Study of TwentySeven Democracies, 1945–1990 (Oxford and New York: Oxford University Press, 1994), pp. 163–77. Generally, the approach adopted here has been the same as Lijphart’s, i.e. when thereported number of total valid votes (or seats) does not equal the sum of the reported votes(or seats) for individual parties, the number used as the basis for calculations has been the sum of the parties’ votes (or seats). (ii) bunching of ‘Others’, i.e. small parties and independents not listed separately. In the calculation of indices, the greater the amount of disaggregation in the data, the better.Ideally, every party winning more than 0.1 per cent of the national vote, certainly 0.5 per cent, should be listed separately. The votes of Independents are very rarely disaggregated, so when they are a significant force (Japan, South Korea), there are problems in trying to compute indices given that each independent candidate should be treated as a separate ‘party’. The approach taken here...